title: Characterization of 23S rRNA gene mutation in primary and secondary clarithromycin-resistant Helicobacter pylori strains from East China.
abstract: OBJECTIVE
  Clarithromycin is an effective antibiotic for treating Helicobacter pylori; however, the development clarithromycin- resistance by multiple strains prevents the eradication of Helicobacter pylori. We aimed to characterize mutations in the 23S rRNA gene of primary clarithromycin-sensitive, primary clarithromycin-resistant and secondary clarithromycin-resistant Helicobacter pylori strains that were collected in East China and elucidate the mechanisms of clarithromycin resistance.
  
  
  METHODS
  The disk diffusion test and E-test method were used to determine the clarithromycin susceptibility of clinical Helicobacter pylori strains. The 23S rRNA gene fragments were amplified by polymerase chain reaction from 18 primary clarithromycin- resistant strains, 15 primary sensitive strains and 8 secondary clarithromycin-resistant strains. Polymerase chain reaction-products were sequenced to determine mutations of the 23S rRNA gene.
  
  
  RESULTS
  We found an A2143G (8 strains) mutation in primary clarithromycin-resistant strains, an A2143T (5 strains) mutation in secondary clarithromycin-resistant strains; but no mutations were found in position 2143 of sensitive strains. A T2182C mutation in primary clarithromycin-sensitive, primary clarithromycinresistant and secondary clarithromycin-resistant strains was found with a prevalence of 86.7% (13 strains), 72.2% (13 strains) or 87.5% (7 strains), respectively. In addition, we found a G2254T (8 strains) and a G2172T (7 strains) mutation in secondary clarithromycin- resistant strains. These point mutations were absent in primary clarithromycin-resistant and -sensitive strains.
  
  
  CONCLUSIONS
  The gene mutation in position 2143 was associated with resistance to clarithromycin, but the mutation was different between primary and secondary clarithromycin-resistant strains. The T2182C mutation was not associated with clarithromycin resistance. Two new hotspot mutations: G2254T and G2172T, in 23S rRNA were discovered in secondary clarithromycin-resistant strains.
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital, Nanchang University, Nanchang, China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Zhen-Hua
authors.forename: Huang
authors.initials: H
authors.lastname: De-Qiang
authors.forename: Xie
authors.initials: X
authors.lastname: Yong
authors.forename: Liu
authors.initials: L
authors.lastname: Lin-Lin
authors.forename: Lu
authors.initials: L
authors.lastname: Nong-Hua
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002681:China / Q000453:epidemiology; D017291:Clarithromycin / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D017354:Point Mutation / Q000235:genetics; D015995:Prevalence; D012329:RNA, Bacterial / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D017291:Clarithromycin